The Overview Page is often used as a landing page for important Spaces/Groups such as an HR places or a Department place. They can be also used in Places to broadcast information.
Whereas the Activity Page is often used for Places containing content for action as well as checking the status of projects. They can be beneficial for Places with heavy use of the 'Structured Outcomes' features.
If you have a scenario where you need to display both structured outcomes as well as specific type of information that widgets can bring, we recommend using both.
This document list the different widgets: https://docs.jivesoftware.com/cloud_int/comm_mgr/jive.help.core/#user/WidgetReference.html
This shows the different tiles: https://docs.jivesoftware.com/cloud_int/comm_mgr/jive.help.core/#user/PlaceTemplatesTileReference.html
A nice thing about tiles is you do have the ability to create a custom tile if needed.
If there is a specific blog that you are interested in promoting using a tile, the Key Content and Places might be a good one you may consider using. This will provide a list of content you can edit and manage yourself that will be displayed to users.
https://community.jivesoftware.com/docs/DOC-150127#jive_content_id_Tiles__Widgets - this document talks a little more about tiles since Jive 7, you may need to request to join The specified item was not found. in order to view it if you are not already a member.
Hope this helps.